Electrical control circuit



June 28, 1955 NE|| 2,712,074

7 ELECTRICAL CONTROL CIRCUIT Filed Jan. 19 1945 2 Sheets-Sheet 1INVENTOR.

2% t 15.1. BY Hu'gk 6.114322 A T TOENE Y June 28, G N

ELECTRICAL CONTROL CIRCUIT Filed Jan.

2 Sheets+Sheet 2 YLD INVENTOR. Hugh 'AZ A T TO/TNE Y ions havingdifferent mass-energy properties.

2,712,074 Patented. June 2-8, 1955 ELECTRICAL CflNTRQL CERGUIT Hugh G.Neil, Gal: Ridge, Tenn, assignor, lay mesne assignments, to the Unit-edStat-es of America as represented by the United States Atomic Connmission Application January 19, 1945, Serial No. 573:,615

5 Claims. (Ql. 25tl41.9)

The invention described herein is concerned with improvements inelectrical control circuit arrangements particularly adaptable for usein isotope separating apparatus, that is, apparatus designed for theseparation of The invention is particularly concerned with equipmentwherein the ion source which forms part of the apparatus includes meansfor volatilizing a material to be ionized by the controlled applicationof heat to tie material.

Heretofore in equipment of this nature it has been the practice tovolatilize the material to be ionized and V to maintain the material ina vapor state by the applicato proceed satisfactorily, it is necessaryto accurately control the amount of vapor of the material which ispresent for ionization. in apparatus of the type referred to above, andas will be made clear in the specification hereinafter, an electrode isprovided in a position adjacent the source of ions, and this electrodeis maintained at a high negative potential for accelerating positiveions away from the ion source so that they can be formed into a beam andthe isotopes thereof separated. Some of the ions are collected by thenegative electrode and lose their charge so that a small drain currentflows through the electrode, and the magnitude of this current isproportional to the amount of or the density of the vapor in thevicinity of the ionizing means. Prior to my invention, it has beenrecognized as being desirable to control the volatilization of thematerial to he ionized in response to the drain current just described.Heretofore desirable results have been obtained by controlling aso-called flash heater or radiant type heater in response to the draincurrent through the electrode just referred to, this heater being in aposition to radiate heat directly on to the charge of material to bevolatilized so that the response of the heater to changes in draincurrent would be quick. The object of my invention is to provide animproved control circuit arrangement for controlling the volatilizationof the charge material in response to the drain current, the controlarrangement being such as to not cause interference with the voltageregulation of the accelerating electrode, which, in apparatus of thetype referred to, is maintained at a high constant negative potential.

The manner in which the object of my invention is achieved, and otherobjects and advantages of the invention, will become apparent from thefollowing detailed description and annexed drawings wherein Fig. 1 is adiagrammatic view of an isotope separator of the type which employs anion generator in which the control arrangement of my invention may bepracticed.

Fig. 2 is a diagrammatic sectional view taken along line 22 of Fig. 1.

Fig. 3 is a view of the control arrangement of my invention applied tothe ion producing source which is used in the system of Fig. 1.

Referring to Fig. 1 of the drawing, there is shown diagrammatically anapparatus for isotope separation, the apparatus being of the type whichincludes ion generating means wherein a solid material is volatilized bythe application of heat. My invention is particularly adapted to thecontrol of the application of the heat for volatilizing the material, soas to desirably regulate the amount of vapor present for ionization. Theapparatus of Fig. 1 is of the type disclosed in greater detail in theapplication of Ernest 0. Lawrence, Ser. No. 557,784, filed October 9,1944. The apparatus of Fig. 1 includes a tank 10, the interior of whichis evacuated to a relatively high degree of vacuum as will be presentlydescribed. The tank It) is rectangular in cross section and one side isclosed by a relatively heavy face plate 11 which is attachable to thetank by means of screw clamps 12 and 13, there being provided suitablebearing surfaces on face plate 11 and on the tank 19 so that when theface plate 11 is clamped into position, the tank 10 is attached to andcarried by the face plate 11 as will be presently explained.

The tank It) has windows 14, l5, l6 and 17 so as to make it possible towatch operations within the tank, and it has a large discharge outlet 29through which the air and moisture within the tank are evacuated. Thedischarge outlet 26 is connected to a diffusion pump or pumps 21 by pipe22 and the diffusion pump is connected to a mechanical pump or pumps 23by pipe 24. The mechanical pump 23 may be a Kinney pump for example.This pump is of the rotary type.

The tank 10 is disposed between laminated iron cores or poles 27 asshown in cross section in Fig. 2 and wound around these pole pieces areelectrical windings 28, the windings being disposed within tanks orhousings 29, the housings 2% being shown in cross section in Fig. 1. Thewindings 23 are energized with electric current so that a relativelyintense magnetic field is produced which is in a direction transverse tothe tank 10, that is, a horizontal direction looking at Fig. 2 and in adirection perpendicular to the paper looking at Fig. 1. A cooling mediumsuch as cooled oil or the like is circulated through the housings 29 forthe purpose of cooling the coils therein.

Within the tank it} is a liner structure 35 in the form of an arcuateconduit which forms a passageway for a beam or beams of ions generatedat the lower end of the liner and received in a receiver at the upperend of the liner. The liner 35 is carried by the face plate lit by meansof supporting structure designated by the numerals 36 and 37 and thebrace member indicated by 38 and is supported from insulators 32, 33,and 34. Within the lower right hand corner of the tank 10 there are apair of castings 4t) and 41 which form containers within which amaterial to be ionized is volatilized. These castings are suitablysupported within the tank and since they are identical and the structureand controls associated with each one are identical, only one will bedescribed in detail. My invention is particularly concerned with themanner of control of the volatilizing of the material within thecontainers 4% and 4 the automatic control apparatus for the heatersassociated with the containers 4t and 4f. is shown in detail in Fig. 3.

The casting 41) comprises a lower portion 31 and a smaller upper portion42, the two portions being connected by a converging throat as shown.Within the portion 31 is a container or bottle 43 which is removable andin which the charge material itself is placed, that is, the charge ofmaterial to be ionized. Within the bottle 43 is a flash or radiant typeheater 44 which may be the well known Calrod type of heater consistingof an elec- 0 trical resistance element wound upon a suitable insulatingmember. One end of the heating element is connected to a source of powerand the other end is grounded as will be described, by being connectedto the casting 40 or the like. The vaporized material passes fromportion 31 into portion 42 through a chimney 45, the vaporized materialpassing up and over a baflle member 46 adjacent the entrance end of thechimney 45. At the left end of the portion 42, there is a longitudinalslit 50 through which the vaporized material passes. Disposed at one endof this slit is a cathode 51, as shown in Fig. 3, across the terminalsof which a suitable voltage is impressed when the apparatus is inoperation. The function of the cathode 51 in operation is to emit astream of electrons into and along the slit 50 for the purpose ofionizing the vapor passing therethrough as will be presently described.Numeral 52 designates electric heating elements associated with theportion 42 and to which electrical energy is supplied as will bedescribed in connection with Fig. 3, one end of the heating elementsbeing grounded by being connected to the casting 40 for example. Numeral53 designates a well in a sidewall of the portion 42 in which athermocouple is located, the thermocouple being for the purpose ofcontrolling the supply of heat to the heating elements.

To the left of the casting 40, that is above it, is a member 56 whichmay preferably be made of carbon and which has therein a slit parallelto the slit 50 so that the vapor emitted through the slit 50 can alsopass through the slit in 56. The electrode 56 constitutes anaccelerating electrode for positive ions emerging from the slit 50 andthis electrode is maintained at a relatively high negative potential aswill presently be described.

The ions accelerated by the electrode 56 pass to the left, that isupwardly, through another slit in a member 57 forming a throat, and theslit in this throat is also in the form of an electrode 58 made ofcarbon and it is main tained at a relatively high negative potentialsomewhat lower than the potential of electrode 56. Positive ions afterpassing through the throat 57 pass into the liner structure 35 and thentravel in arcs of a circle around through the liner to the receivingstructure at the opposite end of the liner; the positive ions move inarcs of a circle in this manner under the influence of the magneticfield previously described and the radii of the arcs depends upon themass-charge properties of the ions.

There are two identical receiving chambers at the upper end of the linerstructure 35, one of them being designated by the numeral 60. Thereceiving chamber 60 is in the form of a box having a shape which incross section is as shown in Fig. 1. The receiver 60 may be adjustedlaterally relative to the face plate 11 by stem 61 operating throughlinkages 62, and it may be adjusted in and out relative to the faceplate by means of stem 63, the stems passing through suitable sealingdevices 64 and 65 respectively associated with the face plate 11. Thereceiver 60 has pockets 71 and 72 therein which are so located as toreceive certain components of the beam of ions which travels aroundthrough the liner 35, different components of the beam, that is,particles having different mass-charge properties, travelling in circlesof different radii as described above. Within the pockets 71 and 72 areelectrodes 73 and 74 respectively which are maintained at a certainpotential which will presently be referred to.

The face plate 11 is grounded as shown as are the castings 40 and 41,and the liner 35 and the electrode 58 forming part of throat 57 aremaintained at a relatively high negative potential V1 by conductor 75which is led into the interior of the tank through a conduit 76 whichextends through the face plate through a sealing insulator bushing 77.The electrode 56 is maintained at a higher negative potential V1+Vz bymeans of a conductor 78 which is also led into the tank through thebushing 77 and the conduit 76. The electrodes 73 and 74 are maintainedat the potential V1 by means of conductors 79, 80, and 81. Theconductors leading to the electrodes in the receiver 60 extend through aconduit and bushing similar to those for the conductors 75 and 78 asshown. A potential V3 is across the terminals of the cathode 51 and aVolt- '4 age V4 is impressed between the negative terminal of cathode 51and ground, that is the casting 40. This latter potential sustains theare which is struck within slit 50 during operation.

Summarizing the operation of the apparatus as so far described, theoperation is that charge material in the bottle 43 is vaporized by theradiant heater 44 and the vapor passes up into the upper portion 42 ofthe casting where it is maintained in vapor state by the heatingelements 52. The vapor passes up through the slit Where it is ionized bythe stream of electrons from the cathode 51, an are being formed in theslit 50 under the influence of voltage V4. Positive ions are attractedfrom the region of the slit by electrode 56 which is maintained at anegative high potential, and under the influence of electrode 58, theions pass into the liner structure 35 and thence travel in arcs of acircle around to the receiver 60, the radii of the arcs depending uponthe mass-charge properties of the ionized particles. The receiver isadjusted as described so that the desired isotopes of the ionizedmaterial is received in the collector pockets.

With reference to the structure so far described, it will be understoodthat those elements which are maintained at high potentials are suitablyinsulated from other elements at lower or ground potential. Also variousof the parts within the tank 10 may be cooled as desired by a suitablefluid cooling system and shielding may be provided at appropriate pointsto protect the mechanism from becoming coated as a result of beingcontacted by the vapor from the charge bottle and for protection fromdeterioration which may necessarily result from the process.

Referring now to Fig. 3 of the drawing, this figure shows the automaticcontrols for the heaters associated with the castings 40 and 41 wherebythe volatilization of the material to be ionized is controlled. Duringthe process some of the positive ions are collected by the electrode 56and lose their charge so that there is a small current flow through thecircuit of this electrode. In order that the process proceed desirablyand efliciently, the quantity of vapor present for ionization must beaccurately controlled and the amount of current in the circuit ofelectrode 56, that is, the drain current, is an accurate indication ofthe amount of vapor present for ionization. The objective of myinvention as stated above is to provide an improved control circuitarrangement whereby the volatilization of the material to be ionized maybe appropriately controlled in response to the drain current through thecircuit of electrode 56. The details of this circuit will presently bedescribed.

The heating elements 52 serve the purpose of maintaining the chargematerial in its vapor state in the portion 42 of casting 40, that is,they prevent the material from condensing within this portion. Theheaters 52 as pointed out above are grounded at one end by beingconnected to the casting 40 and they are otherwise connected by a wire83 to one winding 84 of a transformer 85 having another winding 86. Theother terminal of the winding 84 is grounded as shown. The supply ofpower to the heaters 52 is controlled by a control system including athermocouple 87 disposed in the well 53, which is connected to a controlinstrument 88 by leads as shown. The control instrument 88 is one of anysuitable type such as the Micromax manufactured by the Leeds & NorthrupCompany. This instrument is a potentiometer type of instrument which isadjusted in response to the temperature affecting the thermocouple 87.The instrument 88 is connected to another instrument 89 so as to impressa signal thereon and this instrument is an electronic type ofinstrument, preferably one embodying a thyratron, which controls thepower supplied to the winding 86 of transformer 85. The instrument 89may preferably be the Reactrol control manufactured by General ElectricCompany. Thus, the energization of winding 86 is controlled in responseto the temperature affecting thermocouple 87 and in turn the power inwinding 84 is controlled proportionately so that the energy supplied tothe heaters 52 is controlled by thermocouple 87 in a manner to maintaina constant temperature within the portion 42 of casting 40.

The voltage which is impressed on electrode 53 is supplied from aregulated kv. supply V1 indicated diagrammatically at 93, the positiveterminal of this supply being connected to ground as shown. Thepotential impressed on electrode 56 is supplied from the supply 93 and asecond 15 kV. supply V2 so that the voltage on electrode 56 is KV.Connected between the supplies 93 and 94 are two transformers 95 and 96,that is, the primary windings 97 and 98 of these transformers areconnected between the supplies 93 and 94 and these windings areconnected in opposition so that there is no resultant current flow inthe circuit resulting from the transformers. The transformers have otherwindings 99 and 100 which are connected in parallel as shown and to aprimary winding 101 of a transformer 102 having a secondary winding 103,

the primary winding 101 of this transformer being insulated for 50 kv.The winding 103 is connected to an auto-transformer 105 and to theprimary winding 106 of a transformer forming part of a conventional D.C. power supply 107. The power supplied to the auto-transformer 105 isfrom a regulated volt source and this source supplies power directly tothe primary winding 109 of a transformer forming part of a secondconventional D. C. power supply 110. The outputs of the power supplies107 and 110 pass through conventional filtering arrangements and theseoutputs are connected in opposition by means of voltage dividers 111,112, and 113 so that the difierence between the amount of the outputs ofthe two power supplies is impressed across a voltage divider 114, theslider of which connects to the grid of a control tube 115. It should benoted that the positive voltage output of power supply 107 is connectedto ground at 130, and that the center taps (the negative sides) of boththe power supplies 107 and 110 are connected together and to a point 131on the voltage divider comprised of the adjustable resistances 111, 112,114, and 113 which are connected from the positive voltage output 132 ofthe power supply 110 to the ground connection 130. By suitably adjustingthe resistances 111, 112, 114 and 113 the opposed voltage outputs ofpower supplies 107 and 110 may be balanced to obtain a desired negativepotential with respect to ground at the slider 133 of resistance 114 forpredetermined input voltages to the primary 106 of power supply 107 andprimary 109 of power supply 1110. Thereafter, should the voltage inputto the primary 106 change, as will be described, the negative potentialwith respect to ground at the slider 133 will accordingly be changed inview of the opposed connection of the power supplies 107 and 110 asshould be readily understood. Power for the tube 115 is supplied from aconventional D. C. power supply designated by 116, the transformer ofwhich is energized from the 110 volt source previously referred to. Theplate circuit of the control tube 115 controls the winding 117 of arelay 118 and the contacts of this relay control the supply of powerfrom a transformer 119 to two auto-transformers 120 and 121 connected inparallel, these transformers being of the type known commercially asvariacs. The autotransformer 121 controls the supply of power to theheater 44 within casting 40 and the auto-transformer 120 controls thesupply of power to the corresponding heater in the casting 41. Theslider of auto-transformer 121 connects by wire 125 to the electricheating element 14, the other end of this element being grounded bybeing connected to the casting 40 as described above. One terminal ofeach of the auto-transformers is also grounded as shown on Fig. 3.

In the operation of the circuit arrangement of Fig. 3, there is a smallcurrent flow as described above through the circuit of electrode 56 andthis current passes through the windings 97 and 98 of transformers 95and 96 tending to saturate the cores of these transformers and therebyvarying their impedance. The current in windings 99, 100 and 101 variesaccordingly, and the result of this is a change in voltage drop acrosswindings 103 and 106. The change in voltage across winding 106 variesthe output of power supply 107 so that the output of this power supplywhich is opposed to power supply 110 is changed in proportion to thecurrent in the circuit of electrode 56. The signal voltage which isimpressed on the control grid of control tube 115, and which isdependent upon the difference between the outputs of power supplies 107and 110, is therefore changed in proportion to the drain current in thecircuit electrode 56. Upon a decrease in drain current from theelectrode 56 due to a reduction in the amount of volatilized materialthere is a voltage change in the primary 106 changing the voltage outputof power supply 107 and making the potential at the power supply at theslider 133 less negative and the grid of tube 115 more positive; thecurrent flow through the control tube is increased so as to energize thewinding 117 of relay 118 sufficiently to pull in the relay closing thecircuit to the auto-transformers 120 and 121, and the auto-transformersthen in turn energize the heaters 44. Heater 44 radiates directly on tothe charge material in the bottle 43 so as to vaporize it and increasethe amount of volatilization, and this increased amount of vapor willpass up into the portion 12 of casting 40 which will result in anincrease in drain current flow in the circuit of electrode 56, whichwill in turn result in a signal being im ressed on the grid of tube 115making the grid less positive so as to decrease the current flow throughthe control tube 115 and de-energize the relay 118 cutting off the powerfrom the auto-transformers 120 and 121. This de-energizes the heaters44. Thus the control arrangement operates in an on and oil manner toregulate the amount of volatilized material which passes up into theportion 42 of casting 40 to be ionized. The voltage impressed on thegrid of tube 115 may be manually adjusted by adjusting the slider ofvoltage divider 114 and thus the control point of the circuit can bevaried. By adjusting the voltage dividers 111, 112, and 113, the voltageimpressed on voltage divider 114 can be adjusted and thus in this mannerthe sensitivity of the control circuit may be suitably varied.

From the foregoing it is to be seen that my circuit arrangement providesan effective means for controlling the volatilization of the chargematerial and that the arrangement is such that the control means doesnot produce a current flow in the circuit of electrode 56 and it doesnot affect the voltage regulation of the electrodes 56 or 58.

The embodiment disclosed herein is a preferred form of my invention andit is intended that it be interpreted in an illustrative rather than alimiting sense. It is intended that the scope of the invention bedetermined only in accordance with the claims appended hereto.

I claim:

1. In apparatus of the character described, in combination, meansforming an ion source, an electrode adjacent said source, means formaintaining said electrode at a relatively high negative potential, andmeans responsive to current fiow through said electrode controlling saidion source, said last means comprising transformers having windingsconnected in opposition in circuit with said electrode, and meanscomprising an electronic device coupled to said transformers to receivetherefrom a control impulse for controlling said ion source.

2. In an electrical control system wherein it is desired to control froman electrical element which is held at a relatively high constantvoltage, in combination, means comprising a pair of transformers havingwindings connected in opposition in circuit with the electrical elementwhich it is desired to control from, means comprising two sources ofrectified power supply having their outputs connected in opposition,means for impressing a signal on the input to one of said power supplieswhich is proportional to the current in said windings, and meanscomprising a controlling element responsive to the difference betweenthe outputs of said power supplies which are connected in opposition.

3. In apparatus of the character described, in combination, meansforming an ion source including a source of heat for vaporizing materialto be ionized, an electrode adjacent said ion source, means formaintaining said electrode at a relatively high negative potential, andmeans responsive to current flow through said electrode for controllingsaid heat source, said last means comprising transformers havingwindings connected in opposition in circuit with said electrode, andmeans comprising an electronic device coupled to said transformers toreceive therefrom a control impulse for controlling said heat source.

4. In apparatus of the character described, in combination, meansforming an ion source including a source of heat for vaporizing materialto be ionized, an electrode adjacent said ion source, means formaintaining said electrode at a relatively high negative potential, andmeans responsive to current flow through said electrode for controllingsaid heat source, said last means C0111- prising transformers havingwindings connected in opposition in circuit with said electrode, meanscomprising two sources of rectified power supply having their outputconnected in opposition, means for impressing a signal on the input toone of said power supplies which is proportional to the current in saidwindings, and means comprising a controlling element responsive to thedifference between the outputs of said power supplies for controllingsaid heat source.

5. In an electrical control system wherein it is desired to control froman electrical element which is held at a relatively high constantvoltage, in combination, means comprising a pair of transformers havingwindings connected in. series opposition with each other and in circuitwith the electrical element which it is desired to control from, andmeans comprising an electronic control circuit having said transformerscoupled thereto whereby a control impulse from said transformers isimpressed on said control circuit.

References Cited in the file of this patent UNITED STATES PATENTS1,406,328 Atherton Feb. 14, 1922 2,179,333 Horsley Nov. 7, 19392,221,467 Bleakney Nov. 12, 1940 2,227,353 Kuntke Dec. 31, 19402,319,378 Weisglass May 18, 1943

